Broken rear derailleur mount

I recently had an "incident" with some ice and the attached pics shows the result. This is a Cannondale F1000 (1999 or so). My question is, how easy is it going to be to find a replacement part for this? Are there sites that would actually sell such a specific item?

I'd rather ask here and try to do it myself than take it in to the local shop as I don't really trust there opinion on things. I'm sure they would try to get me to buy a whole new derailleur or something when it appears (to me) the derailleur is fine.

I would contact Cannondale to find out if the derailleur hanger is stilll available as a part and the part number. It looks like the hanger is a replaceable bolt on item that any Cannondale dealer should be able to obtain for you if it is still available.